It is neither 'assigned' nor 'observed'. There are countless number of animals born every day that have well-defined sex, although nobody assign or observe that

It is neither 'assigned' nor 'observed'. There are countless number of animals born every day that have well-defined sex, although nobody assign or observe that. Humans are just subset of animals, so same definitions apply. > Moreover, what you're really saying is that transgender people don't exist This subthread is about sex, not gender. AFAIK, transgender people just have different gender that one associated with their biological sex.